Chalcogen Stabilized bis‐Hydridoborate Complexes of Cobalt: Analogues of Tetracyclo[4.3.0.0^2,4.0^3,5]nonane

Abstract

Treatment of Li[BH3ER] (E=Se or Te, R=Ph; E=S, R=CH2Ph) with [Cp*CoCl]2 led to the formation of hydridoborate complexes, [{CoCp*Ph}{Cp*Co}{μ‐EPh}{μ‐κ2‐E,H‐EBH3}], 1a and 1 b (1 a: E=Se; 1 b: E=Te) and a bis‐hydridoborate species [Cp*Co{μ‐κ2‐Se,H‐SeBH3}]2, 2. All the complexes, 1 a, 1 b and 2 are stabilized by β‐agostic type interaction in which 1 b represents a novel bimetallic borate complex with a rare B−Te bond. QTAIM analysis furnished direct proof for the existence of a shared and dative B‐chalcogen and Co‐chalcogen interactions, respectively. In parallel to the formation of the hydridoborate complexes, the reactions also yielded tetracyclic species, [Cp*Co{κ3‐E,H,H‐E(BH2)2‐C5Me5H3}], 3 a and 3 b (3 a: E=Se and 3 b: E=S), wherein the bridgehead boron atoms are surrounded by one chalcogen, one cobalt and two carbon atoms of a cyclopentane ring. Molecules 3 a and 3 b are best described as the structural mimic of tetracyclo[4.3.0.02,4.03,5]nonane having identical structure and similar valence electron counts.

Bimetallic Perthiocarbonate Complexes of Cobalt: Synthesis, Structure and Bonding

“…Ltd., Mumbai, India), were purchased and used as received. The complexes [{Cp*CoPh}{ µ -TePh}{ µ -TeBH 3 - ĸ 2 Te,H}{Cp*Co}] ( 1 ) [ 19 ] and [Cp*VCl 2 ] 3 ( 4 ) [ 45 ] were prepared according to the methods from the literature. Dialuminum-supported TLC plates (MERCK TLC plates, Bangalore, India) were used for the separation of the reaction mixtures.…”

“…Despite being largely uncontrolled, the isolation of numerous unique metallaheteroboranes demonstrating novel coordination modes prompted us to investigate this area more meticulously. In this context, our group utilized three distinct strategies: (i) pentamethylcyclopentadienyl-based metal halides with chalcogen-based borate ligands such as [LiBH 2 E 3 ], [LiBH 3 EPh] (E = S, Se, Te), [LiBH 4 + CS 2 ], or [NaBH 4 + CS 2 ] [ 19 , 20 , 21 ]; (ii) preformed metallaboranes with the above chalcogen-based borate ligands [ 21 ]; and (iii) preformed metallaboranes with CS 2 or CS 2 -based ligands such as [CS 2 ·PPh 3 ] [ 22 , 23 ]. In our earlier reports, the classical diborane [B 2 H 5 ] − was stabilized by the reaction of [Cp*TaCl 4 ] with [LiBH 4 ·THF], followed by the addition of excess [S 2 C·PPh 3 ] adduct [ 23 ].…”

“…Very recently, the reactivity of a borate ligand derived from CS 2 with κ 2 -N,S-chelated ruthenium borate complexes, [Ph 3 P( κ 2 -N,S-L)Ru{ κ 3 -H,S,S′-H 2 B(L) 2 }] (L = C 7 H 4 NS 2 , C 5 H 4 NS), has been investigated [ 24 ]. Therefore, we pursued this chemistry, reacting the cobalt borate complex [{Cp*CoPh}{ µ -TePh}{ µ -TeBH 3 - ĸ 2 Te,H}{Cp*Co}] ( 1 ) [ 19 ] with CS 2 . Although the objective of obtaining transition metal complexes containing boron content was not achieved, interesting cobalt and vanadium thiolate complexes were isolated.…”

Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes

“…By applying the same synthetic strategy to [Cp*CoCl] 2 , we isolated the bimetallic σ-borate complexes [(Cp*CoPh)­(μ-EPh)­{μ:η 2 - E , H -EBH 3 }­(Cp*Co)] (E = Se ( 38a ), Te ( 38b )) and [Cp*Co­{μ:η 2 - Se , H -SeBH 3 }] 2 ( 39 ) (Scheme ). The structures of 38a , 38b , and 39 reveal a nearly planar {Co 2 E 2 } metallaheterocyclic ring with torsion angles ranging from 0° to 2.13° (Figure ). The Co···Co distances of 3.5065(7) Å ( 38a ), 3.7676(8) Å ( 38b ), and 3.5020(6) Å ( 39 ) are considerably longer than the sum of the covalent radii (2.52 Å) and thus exclude the possibility of Co–Co bonds.…”